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Most Important Selected Qs for JEE AdvancedMathematicsTrigonometry

Let = _ k=1 ²⁰ ( 3 k ) 4 ^2 ( k 9 )-1 and = _ k=1 ²⁰ ( 3 k ) 1-4 ^2 ( k 9 ) . If ^2- ^2=1+ ^ then find the value of .

Correct answer

20

Step-by-step solution

= 9 + 2 9 + 3 9 + + 20 9 = (20 18 ) 18 ( 21 18 )= 18 = 10^ array rlrl IIhy & & = 3 18 = 3 10^ ^2- ^2 & =2 ^2 10^ =1+ 20^ 1+ ^ & =20 array

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